This invention relates to retractable casters, and more particularly to retractable casters which are oftentimes utilized to support a relatively heavy object, such as a power tool (e.g., a radial arm saw or table saw), on rollers or casters so that the object may be readily rolled to a desired location, then the casters may be retracted so that the object or machine rests solidly on the floor during operation.
Heretofore, certain prior art retractable casters included a caster frame securable to the frame of the power tool support stand. Each of these prior art retractable caster assemblies included a caster which was selectively raised and lowered by means of a screw jack arrangement provided on the stem of the caster (see FIG. 1). However, this screw jack arrangement was required to be operated by hand and took a considerable time (e.g., a minute or more) to raise and lower each caster. Of course, since the screw jack was located near floor level, operation thereof required the operator to bend over in an uncomfortable position for the several minutes required to operate the several casters as are typically installed on the power tool. Still further, the casters would not always be uniformly lowered to the same level when in their lowered positions so that the power tool would rock on the casters.
Another known prior art, foot actuated, retractable caster arrangement involved the use of shaft journalled at each end of the power tool support stand near floor level. This shaft was rotated by means of a foot pedal or lever and the shaft carried a pair of rotary cams which cammingly engaged casters so as to force them downwardly and to lift the support stand up from the floor. Typically, one of these cam shafts and a pair of retractable casters was provided at each end of the power tool support stand. Upon rotation of the cam shaft and cams in opposite direction, the caster was permitted to move downwardly and to bear solidly on the floor. While this foot operated retractable caster arrangement could optionally be fitted on a power tool support stand (i.e, retrofitted thereon), it is relatively expensive to manufacture and cannot be readily adapted to fit a variety of machine frames and different sizes of power tool support frames.
Still further, reference may be made to U.S. Pat. No. 3,687,239 issued to W. G. Moehlenpah which discloses rollers raised and lowered by means of a foot operated pedal for rollingly supporting a work stand on a track. This last mentioned roller arrangement is broadly similar to the above-mentioned foot operated retractable caster arrangement intended for use with power tool support stands or the like.
Among the several objects and features of the present invention may be noted that the provision of a retractable caster assembly adapted to be readily installed on an object (e.g., on a power tool support stand or the like) which when in its lowered position rollingly supports the object and which when retracted permits the object to rest solidly on the floor;
The provision of such a retractable caster assembly which is foot operated, which may be quickly raised and lowered, and which is consistently and accurately moved to a predetermined lowered position;
The provision of such a caster assembly which automatically and positively locks the caster in its lowered position when the retractable caster is actuated;
The provision of such a caster assembly which may be readily adapted for use with a wide variety of sizes and designs of objects to be supported thereby;
The provision of such a caster assembly which is of rugged and economical construction, which is economical to manufacture, and which is reliable in operation.
Other objects and features of this invention will be in part apparent and in part pointed out hereinafter.